1. Field of the Invention
The present invention relates generally to an acoustic wave therapy apparatus for treating cancerous cells or calculi in a human body, using shock waves produced by acoustic waves or continuous acoustic waves, and more particularly to an ultrasonic shock wave lithotripsy apparatus and an ultrasonic continuous wave hyperthermic therapy apparatus.
2. Description of the Related Art
Conventional ultrasonic treatment apparatuses include an ultrasonic shock wave lithotripsy apparatus for breaking calculi, etc. in a human body, using shock waves due to focusing ultrasonic energy, and an ultrasonic continuous wave hyperthermic therapy apparatus for treating a tumor by heating it up to a lethal temperature, using continuous focusing ultrasonic energy.
This type of ultrasonic treatment apparatus generally has an acoustic wave generator for generating ultrasonic waves. The acoustic wave generator has a concave surface for focusing the generated ultrasonic waves. The acoustic wave generator is arranged to face a subject, with a bag interposed therebetween. An ultrasonic imaging probe is arranged within the bag, for positioning the acoustic wave generator and for obtaining tomograms of the subject for confirming the result of treatment.
If a large-diameter acoustic wave generator is employed in this apparatus and generated waves are focused onto a region-of-interest (ROI), a maximum treatment effect is attained with a small treatment energy. In this case, however, if the focus of waves departs from the ROI, a normal tissue is damaged. It is thus important to precisely focus the waves onto the ROI.
FIG. 1 is a cross-sectional view schematically showing an acoustic wave therapy apparatus having this type of imaging means. In FIG. 1, irradiation devices (as the acoustic wave generator) 10 and 12 serving as acoustic wave generators are secured to a holder 14. The irradiation devices 10 and 12 are arranged symmetrically with respect to an ultrasonic imaging probe 18 (described later) so that the focal points of the devices 10 and 12 may be positioned at a region-of-interest (ROI) 16. The acoustic wave therapy apparatus has a bag member 22 containing water 20 which is put in close contact with a surface 26 of a subject 24. The ultrasonic imaging probe 18 is arranged at the center of the holder 14 and is employed for effecting positioning for treatment and for receiving ultrasonic waves reflected from the ROI 16, thereby confirming if the ROI 16 has been treated appropriately. In FIG. 1, a dot-and-dash line indicates a region where ultrasonic waves for treatment are radiated, and a two-dot-and-dash line indicates a region where ultrasonic waves for ultrasonic imaging treatment are radiated.
When an acoustic wave therapy is performed by this apparatus, ultrasonic waves are radiated onto the ROI 16 in the subject 24 and the ultrasonic imaging probe 18 receives the waves reflected by the ROI 16. Tomograms are formed on the basis of the reflected waves, and the formed tomograms are displayed. Observing the tomograms, an operator moves and positions the apparatus so that the focal points of the irradiation devices 10 and 12 coincide with the location of the ROI 16. When the focal points of the devices 10 and 12 coincide with the location of the ROI 16, the devices 10 and 12 are driven to radiate intense ultrasonic waves onto the ROI 16, thereby treating the ROI 16.
As has been stated above, the ultrasonic imaging probe 18 is put on the surface 26 of the subject 24 via the water bag 22, manually or by means of an electric mechanism, thereby focusing the waves radiated from the devices 10 and 12 at the ROI 16 and confirming the result of treatment.
In the above-described prior art, however, the operator is unable to sense the intensity of the pressure under which the imaging probe 18 is pressed on the subject 24. Thus, if the operator presses the imaging probe 18 under high pressure for obtaining better tomograms, there is a concern that the subject may be injured.